Fluid heater



J. C. SHARP FLUID HEATER Filed-Feb 16. 1940 Fig I.

July 1, 1941.

Inventor:

@sha p, by .V Kiwi HIS Attorney.

Patented July 1, 1941 FLUID HEATER John C. Sharp, Glen Ellyn, Ill., assignor to Edison General Electric Appliance Company, Inc., a corporation of New York Application February 16, 1940, Serial No. 319,291

Claims.

My invention relates to electric fluid heaters and more particularly to electric Water heaters and it is an object of my invention to provide a heater of this type which is simple in construction, may be manufactured at low cost, and is constructed and arranged so that the elements of the heater may be readily applied to and. removed from the fluid tank.

While not limited thereto, my invention more particularly relates to electric fluid heaters of the push-through type; that is, of the type in which a single valve is placed in the cold water supply line and operation of this Valve controls the quantity of hot water issuing from the hot water outlet.

It is an additional object of my invention to provide a fluid heater of this type with a new and improved means for preventing dripping of the hot water outlet after the valve in the cold water supply line has been closed.

In accordance with my invention, I have provided a new and improved fluid heater comprising a tank provided with an opening, and having a cover plate for closing the opening. This cover plate is constructed and arranged so that all of the component elements of the water heater, including the heating unit, the temperature control device for the water heater, the cold fluid inlet, and the hot fluid outlet, may be mounted on the closure plate and applied to and removed from the fluid heater as a unit. Thus the component elements of the water heater con stitute a unitary assembly and are readily mounted on and applied to the fluid heater tank. Also in accordance with my invention, means are provided for preventing dripping at the hot water outlet after the cold water inlet has been shut oil. This means comprises a small tube which extends into a dome-shaped portion provided at the upper end of the tank. This tube serves as an air vent which insures that the level of the water in the tank will be lowered a sulficient amount after each use so as to prevent dripping from the hot Water outlet during the recuperation period.

For a more complete understanding of my invention, reference should be had to the accompanying drawing in which Fig. 1 represents a side elevation partly in section of my improved water heater; Fig. 2 is a rear elevation partly in section of my improved water heater construction; and Fig. 3 is a bottom view partly in section of my improved water heater construction.

Referring to the drawing, it will be observed that my improved fluid heater comprises a substantially cylindrical tank Ill which is suitably supported in a casing II by means of brackets I la. In order to reduce the heat losses from the tank ID, the space between the tank and the casing is filled with some suitable insulating ma 'terial I2 such as rock wool or the like.

The tank I0 is provided with an opening I2a, which preferably is located at the bottom, and is provided at the top with a formed expansion chamber I3 having a cross sectional area relatively smaller than the cross sectional area of the tank. Provided within the lower end of the tank I0 is a heating element I4 which is preferably of the sheathed type such as described and claimed in United States Letters Patent No. 1,367,341 to C. C. Abbott, dated February 1, 1921. Briefly, this heating unit comprises a coiled resistance element I5 which is encased by a metallic sheath I6 and which is embedded in and supported in spaced relation with reference to the sheath by means of a suitable heat refractory electrically insulating material H, such as powdered magnesium oxide. Also extending within the lower end of the tank I0 is a suitable immersion type temperature responsive element I8 which is adapted to control the energization of the heating element I4 in accordance with temperature changes of the liquid within the tank The particular fluid heater shown in the drawing is of the push-through type; that is, the flow of hot fluid from the tank is controlled or regulated by the fiow of cold fluid into the tank. T0 effect this control I have provided a cold water inlet pipe I9 and a hot water outlet pipe 2|. Provided in the cold water inlet pipe I9 is a suitable valve 2E3 for controlling the cold water supply to the tank. The cold water supply pipe extends a short distance into the bottom of the tank and in order to diffuse the cold water, the end of the pipe is closed and a plurality of openings I9a is provided around the periphery of the pipe adjacent the closed end. The hot water outlet tube extends through the tank and is provided at its upper end with a curved portion 22 which extends into the chamber I3 provided at the top of the tank. As previously stated, the cross-sectional area of the chamber I3 is less than that of the tank. The reason for this reduction in crosssectional area is to increase the height of the chamber so that the height of the curved portion 22 of the outlet tube may be increased with a view to minimizing manufacturing errors at this point.

Arranged to close the opening IZaof the tank It] is a cover plate 23 which is secured to the tank by means of a plurality of bolts 24 and is sealed by means of a suitable gasket 25. In most water heater constructions, the problem of assembling the component elements of the water heater and of cleaning the water heater are of importance both from the standpoint of cost of manufacture and also from the standpoint of ease of inspection, cleaning or repairing of the heater. In accordance with my invention I have constructed the cover plate 23 so that all of the component elements of the liquid heater may be supported thereon to form a unitary assembly which can be removably secured to the tank in by means of bolts 24.

In effecting this construction and arrangement, a plurality of openings are provided in the cover plate. Threadedly supported in one of these openings is the fluid inlet pipe 39. Provided opposite the inlet pipe opening is a second opening into which is threaded a bushing 26 through which is passed the fluid outlet tube 2!, the tube 2| being soldered to the upper or inside edge of the bushing 26 in order to produce a fluid-tight connection. In order to mount the heating element on the cover plate, a bushing 21 is swaged or pressed onto each end of the heating unit, These bushings are adapted to pass through a pair of openings provided in the cover plate and the lower end of each bushing is threaded to receive a nut 28 for drawing the collar portion of the bushing down against the cover. In order to make these joints fluid-tight, a suitable gasket 29 is located between the collar and the cover plate. The temperature control device is mounted on the cover 23 in a manner similar to the heating unit it. With the component elements of the fluid heater thus mounted on the cover plate, inspection, cleaning or repairing of the device as well as its original assembly are greatly facilitated.

The electrical leads 35 for the heater element and temperature responsive control device for the water heater are adapted to enter the top wall of the casing H and pass down through the ins-ulating material 52 along the side of the tank H] to the respective terminals of the heating unit and temperature responsive element. A bushing 3| is provided for insulating the electrical leads from the top wall of the casing l I and a bracket 32 is welded to the tank l0 in order to serve as a guide for the lower end of the leads. The manner in which the electrical connections to the water heater unit and temperature responsive unit are made is more clearly shown in Fig. 3. In the arrangement illustrated, the temperature responsive element is in series with the water heater unit and directly controls the unit in response to changes in temperature of the liquid in the tank. Any suitable type of temperature responsive element may be used in my improved water heater but it is preferred to use a temperature responsive element which may be immersed in the fluid in that such an element may also be mounted on the cover plate 23. It is to be understood, however, that my invention is not limited to this type of temperature responsive element since element of the type which can be secured to th outer wall of the tank Ill may be employed for controlling the operation of the heater unit i in accordance with temperature changes.

In assembling the fluid heater, the inlet pipe, outlet tube, heating means and temperature responsive means for controlling the heating means are first mounted on the cover plate in the manner described above, The cover plate is then secured to the tank and it is to be observed that each element is so mounted on the cover plate that when the latter is secured to the tank, the heating means, inlet pipe and temperature responsive means will extend into the bottom portion of the tank whereas the fluid outlet means and particularly the curved portion 22 thereof will lie in the chamber 13. After the cover plate assembly is secured in position, the electrical connections are made in the manner previously described.

While the construction described above may be used with fluid heaters of any capacity, the fluid heater shown is preferably of small capacity and is adapted to be hung on a Wall adjacent the point of use by means of suitable brackets (not shown). In inspecting, cleaning or repairing the fluid heater after use, it will first be necessary to drain the tank. This may be accomplished by breaking the connection to the water supply line through a suitable union 20a placed in advance of the valve 20 and using the valve 20 as a drain valve; the source of water supply will have been turned off previously by any suitable control means (not shown). After the tank has been drained, the leads 30 may be disconnected and the cover plate unbolted and removed a suflicient distance to expose the component elements supported thereon. If it is desired to remove the assembly completely, the cover plate will be moved outwardly sufliciently far to permit the top portion of the outlet tube to be moved out of the tank. If there should be insuflicient room to accomplish this at the particular place where the tank is mounted, the tank may be removed from its supporting means and laid on its side so that the cover plate can be moved outwardly a sufficient distance.

In operation of the heater described above, the flow of hot fluid, such as hot water, from the outlet is controlled by manipulating the valve 20 in the Water inlet. Thus when the valve 20 is opened hot water at the top of the tank will be forced into the opening at the end of the curved outlet tube and will flow down this tube and out of the tank. It is for this reason that the fluid heater is called a push-through type of heater.

After a quantity of hot water has been drawn oil, the temperature control device [8 will function to cause energization of the heating element ii to heat the cold water admitted during the drawing off process. When the r cuperation is completed, that is, when the water or other fluid attains the predetermined desired temperature, the control device functions to deenergize the heating means l4.

With fluid heaters of the push-through type, it has been found that unless some precautions are taken there will be a tendency for water to drip from the hot water outlet during the recu eration period after some hot water has been drawn ofi" This can best be explained by referring to Fig. 2 and assuming that the cold water valve has just been shut off. Under these circumstances, the water in the tank lil stands at a height somewhat above the clotted line A shown in this figure and water will continue to flow from the hot water outlet until a point of equilibrium is reached between the pressure in the dome above the water, tending to cause water to flow through the tube 2i, and the outside or atmospheric pressure. When this occurs, the water level will have fallen to approximately the point indicated by the line A. Now upon applying heat to the body of cold water within the tank, in order to recuperate the water to its predetermined temperature, the water will tend to expand causing it to rise somewhat above the line A. Due to the increased static head, the equilibrium previously established will be upset and water will flow through the tube 2| until equilibrium is again reached. This produces the aforementioned undesirable dripping from the hot water outlet during the recuperation period.

In order to correct this difficulty and to eliminate dripping from the hot Water outlet during the recuperation period, I have provided a vent tube 33 which, as shown in Figs. 1 and 2, extends upwardly through the tank and into the chamber l3 and terminates adjacent the top of the curved portion 22 of the hot water outlet tube. This vent tube is also mounted on the cover plate 23 and to efiect this mounting an opening is provided in the cover plate adjacent the hot water outlet tube and the vent tube is sealed therein by means of solder or some other suitable sealing material. In operation, the tube 33 permits air to pass into the space in the water heater tank between the top surface of the water and the top of the tank. Thus, when the cold water inlet valve 20 is shut off the water will continue to flow through the hot water outlet tube and air will be drawn into the space above the water to replace the water drawn off. With the vent tube 33 in the posi tion indicated, the water will continue to flow from the hot water outlet until the level of the water is lowered to the level indicated by the dotted line B due to the functioning of the curved end of the 'tube as a siphon. With the level of the water thus reduced, the water may expand during the recuperation period without causing any dripping from the hot Water outlet. The amount of expansion permissible, without causing dripping, is represented by the distance between the lines A and B of Fig. 2.

From the foregoing it will be observed that I have provided a liquid heater which is simple in construction, may be manufactured at low cost and may be quickly and readily assembled and inspected. Furthermore, I have provided a liquid heater of the push-through type with new and improved means for preventing dripping from the hot liquid outlet.

While I have shown a particular embodiment of my invention, it is to be understood, of course. that I do not wish to be limited thereto since many modifications may be made, and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and sco e of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

.1. An electr c fluid heater of the push-throu h vpe comprising a t nk havin a chamber of reduced cross-sectional area at one end, heating means and valve controlled fluid inlet means mounted in the opposite end of said tank. fluid outlet means having a bent-over inlet portion extending into said chamber of reduced crosssectional area, .the flow of fluid throwh said outlet means being controlled by the operation of said valve controlled water inlet means, and means open to the atmosphere terminating in said chamber of reduced cross-sectional area above said bent-over portion of said water outlet means for depressing the level of the fluid in said chamber by a siphoning action through said bent-over inlet portion of said outlet means an amount sufiicient to prevent dripping of said fluid through said outlet means during the recuperation period of said fluid heater after a quantity of hot fluid has been drawn off.

2. In an electric fluid heater, a tank open at the bottom end and having an expansion chamber formed in the upper end thereof, a cover adapted to be removably securedto said tank for closing said open end, electric heating means supported on said cover so as to extend into the lower portion of said tank when said cover is secured in position, fluid inlet means supported on said cover so that the discharge end thereof will lie near the bottom of said tank when said cover is secured to said tank, valve means for controlling the flow of fluid in said fluid inlet pipe, fluid outlet means supported on said cover and adapted to extend through said tank, said fluid outlet means having a bent-over inlet portion extending into said expansion chamber when said cover is secured in position, and means supported by said cover and extending into said expansion chamber adjacent said bent-over inlet portion of said fluid outlet means for connecting the space in said expansion chamber above the water level therein to the atmosphere so that after the closing of said valve inlet means fluid will be siphoned through said bent-over portion of said outlet means and the level of the liquid in said expansion chamber Will be lowered an amount sufiicient to prevent dripping of fluid from said fluid outlet means during the recuperation period of said fluid heater after a quantity of hot fluid has been drawn off.

3. An electric fluid heater of the push-through type comprising a tank having an expansion chamber formed at one end and being open at its opposite end, a closure plate adapted to be removably mounted on said tank so as to close said open end, heating means mounted on said closure plate, valve controlled fluid inlet means mounted on said closure plate so that the discharge end thereof lies adjacent the bottom of the tank when said cover is in position, fluid outlet means supported on said closure plate and extending through said tank and into said exponsion chamber, said fluid outlet means having a substantially curved portion lying in said chamber through which hot fluid is adapted to be forced upon the discharge of cold fluid through said valve controlled inlet means, and a vent tub-e supported on said closure plate adjacent said fluid outlet tube and extending into said chamber, said vent tube serving to prevent dripping from said hot fluid outlet during recuperation of said fluid heater.

4. A fluid heater of the push-through type comprising a tank open at the bottom and having an expansion chamber at the top, a cover plate removably mounted on said tank to close said open end, a valve controlled fluid inlet pipe and a heating unit mounted on said cover plate so as to extend into the bottom of said casing, a fluid outlet tube supported on said cover plate so as to extend through said tank, said outlet tube having a curved inlet portion extending into said expansion chamber, and a vent in said expansion chamber cooperating with said curved inlet portion of said outlet tube to prevent dripping of fluid from said outlet tube during the recuperation period of said fluid heater.

5. An electric fluid heater of the push-through type comprising a tank, heating means and fluid inlet means located in the bottom of said tank, fluid outlet means having a bent-over inlet portion located in the upper end of said tank below the top thereof, and means defining an air vent adjacent the top of said tank cooperating with said bent-over inlet portion of said outlet means to prevent the dripping of fluid from said outlet means during the recuperation period of said fluid heater after a quantity of hot fluid has been drawn off.

JOHN C. SHARP. 

